Selectively embossed surface coverings and processes of manufacture

ABSTRACT

Selectivity embossed surface coverings are prepared by mechanically embossing a wear layer which overlays at least one printing ink containing a photoinitiator which has been printed in a pattern or design. The embossed wear layer is subjected to ultraviolet light which causes curing of the wear layer in the surface areas disposed over the printing ink. The product then is fused whereby the mechanical embossing in surface areas which are not disposed over the printing ink relaxes and becomes smooth. In a variant of the invention, a thermoplastic wear layer is employed which can be mechanically embossed in the surface areas which are not disposed over the printing ink with a texture different from the first applied mechanical embossing.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention has to do with a process for manufacturingmechanically embossed synthetic surface coverings and the productsobtained thereby. More particularly, the invention relates to floorcoverings which are mechanically embossed and processed to createselectively embossed surface areas, thereby creating products having amore realistic appearance. These appearances include, for example,ceramic tile, stone, brick, sandstone, cork, wood, and in someembodiments textured lines or grout lines there between, as well ascombinations thereof such as sandstone and ceramic tile, textured woodand smooth ceramic, cork and wood, and stone or slate in combinationwith ceramic tile.

[0003] 2. Description of the-Related Art

[0004] Synthetic surface coverings including sheet flooring, wallcoverings and tile are employed in residential, commercial andinstitutional applications where decorative effects, durability and easeof installation and maintenance are important considerations. Thesesurface coverings can be designed to imitate a variety of masonrymaterials such as ceramic tile, stone and brick or they can be designedwith unique combinations of color, particles and other decorativefeatures that are not available in other types of surface coverings. Inthe current marketplace, consumers are increasingly demanding syntheticsurface coverings with improved textural features such as features whichrealistically imitate not only the textures of materials such as ceramictile, stone, brick, sandstone, cork, wood and combinations thereof, butalso the texture of the grout or mortar which typically is used by amason or other craftsman to fill the joints between such materials tosecure them in their desired position relative to one another.

[0005] The surface covering industry has employed mechanical embossing,chemical embossing, combinations of mechanical and chemical embossing,screen printing and other techniques for years in order to obtain designeffects and textures which meet consumer demands. In U.S. Pat. No. RE.33,599 a process is described for obtaining selective matting onsynthetic coverings by depositing on an expandable or nonexpandablesupport substrate (1) a polymer coating which contains at least onefirst polymerization initiator onto at least a first selected zone and(2) at least one second coating comprised of a crosslinkable monomerwhich contains at least one second polymerization initiator onto atleast a second selected zone. The second zone may encompass at least aportion of the first zone. The first and second initiators are triggeredby distinct “spectral zones”. Following pre-gelling, an overall grainingoperation is carried out over at least a portion of the surface followedby curing the first selected zone and thereby fixing the grainingthereon. Then gelling is carried out to cause the graining in the secondzone to smooth out. The product has a selectively matted appearance.Another method of making differential gloss products is described inU.S. Pat. No. 4,298,646.

[0006] The surface texture effects of the present invention are obtainedby creating relatively deep emboss depths as compared with the shallowgraining or dusting techniques employed to obtain the matted ordifferential gloss effects of the patents noted above. Morespecifically, the present invention is directed to the realisticimitation in surface coverings not only of the surface texture of avariety of masonry materials such as ceramic tile, stone, brick,sandstone, cork, wood and combinations thereof, but also in someembodiments to the realistic imitation of the surface texture of thegrout or mortar in the joints between such materials.

SUMMARY OF THE INVENTION

[0007] In accordance with the present invention, a novel process isprovided for obtaining selective areas of distinctive appearance, e.g.,textured grout lines, on the surface of a synthetic surface covering. Inone embodiment, to obtain such a product a foamable plastic layercontaining a foaming agent is applied over a sheet substrate. Thecombination is then heated to gel the plastic layer without activatingthe foaming agent. A first printing ink containing a photoinitiator isthen applied in a first pattern on the gelled plastic layer. A secondprinting ink containing both an expansion inhibitor and a photoinitiatoris then also applied to the gelled plastic layer in a second pattern,whereupon a portion of the inhibitor migrates into the gelled plasticlayer. Following the printing steps, a liquid curable coating made froma plastisol or organosol and containing an ultraviolet (“UV”) curablephotopolymer, e.g. an acrylic monomer or oligomer, is applied over theentire surface of the gelled plastic layer, including the first andsecond printing inks, whereupon a portion of the photoinitiator in theprinting inks migrates into the curable coating. The curable coating isthen gelled, with or without a cooling step, followed by surfacesoftening through the use of heat. The softened curable coating is thenmechanically embossed overall with a texture, such as that imitatinggrout, whereupon the product is cured by exposure within an enclosure toUV light to set the grout texture in those portions of the curablecoating overlying the printing inks, both of which contain a portion ofthe photoinitiator. Upon exiting the UV enclosure, the product enters afusion and expansion oven wherein that portion of the curable coatingwhich does not overlie the printing inks containing the photoinitiatorsmooths out such that the grout imitating texture disappears in thoseareas. Furthermore, those portions of the gelled plastic layer which donot contain the inhibitor applied with the second printing ink, foam andexpand. The surface of the curable coating which has smoothed out maythen optionally be mechanically embossed a second time but now with atexture which imitates the texture of stone, wood or the like as heretobefore described. A performance coating like acrylic polyurethane isoptionally applied to the surface of the product for additionalprotection against wear. As will be appreciated by one of ordinary skillin the art, more than two printing inks can be used in the process andproduct of the invention and each of the inks can optionally contain aphotoinitiator and/or an inhibitor. Of course, printing inks which donot contain a photoinitiator or an inhibitor can be employed incombination with inks which do contain a photoinitiator and/or aninhibitor in order to obtain desired decorative effects.

[0008] In another embodiment of the invention, printing inks withoutinhibitors are printed in a pattern or design directly onto a substratewhich does not have a foamable plastic layer. The resultant product hasa flat surface with different textures or appearances including, in someinstances, a three-dimensional appearance. In this embodiment, shouldtextured grout lines be part of the pattern or design, the texturedgrout lines will be flush with the top surface of the product, i.e.without relief.

[0009] In still another embodiment of the invention, calendered and/orextruded sheets can be employed in place of the foamable and/or curablecoatings as explained in the detailed description below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a flow diagram of a process of the invention.

[0011]FIG. 2 is a fragmentary sectional view through a product madeaccording to the process illustrated in FIG. 1 prior to applying acurable coating over the gelled plastic layer. This view and those ofFIGS. 3 and 4 are only for illustrative purposes and it is not intendedthat the thickness of the various layers of components shown are drawnto scale.

[0012]FIG. 3 is a fragmentary sectional view through a product madeaccording to the process illustrated in FIG. 1 at the time of the UVcuring step.

[0013]FIG. 4 is a fragmentary sectional view through a product madeaccording to the process illustrated in FIG. 1 after the secondmechanical embossing step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Referring to FIG. 1, a foamable plastic layer containing afoaming agent is applied over a sheet substrate. The combination is thenheated to gel the plastic layer without activating the foaming agent. Afirst printing ink containing a photoinitiator is then applied in afirst pattern or design onto the gelled plastic layer using conventionaltechniques. A second printing ink containing an expansion inhibitor anda photoinitiator, e.g. an ultraviolet radiation polymerizationinitiator, is then applied to the gelled plastic layer in a secondpattern or design, again using conventional techniques, whereupon theinhibitor present in the second printing ink migrates into the gelledplastic layer beneath the second printing ink. The inhibitor must bechosen so that the rate at which it will migrate from the secondprinting ink into the gelled plastic layer is compatible with the speedof the overall process of making the surface covering. It will beappreciated that the second ink pattern may advantageously be a jointbetween two tiles so as to imitate ceramic tiling. However, the presentinvention is not limited to such a design and may represent any desireddesign. It will also be appreciated that the terms “first printing ink”and “second printing ink” serve only to differentiate the inks and donot necessarily refer to the order in which they are applied to thegelled plastic layer or directly to the substrate neither does it implythat there are only two printing inks to achieve the desired productpattern in the desired colors.

[0015] A clear liquid curable coating containing a UV crosslinkableacrylic monomer or oligomer and optionally a thermal crosslinkinginitiator, e.g., a radical generator such as peroxide is next appliedover the entire surface of the gelled plastic layer including the firstand second printing inks. The photoinitiator residing in the first andsecond printing inks subsequently migrates into the curable coatingwhich has been applied over the inks. The photoinitiator must be chosenso that the rate at which it will migrate from the printing inks intothe curable coating is compatible with the speed of the overall processof making the surface covering. The combination of substrate, plasticlayer, first and second printing inks, and liquid curable coating isthen heated to gel the curable coating. The surface of the curablecoating is then softened by heat whereupon the softened curable coatingis mechanically embossed with an overall textured roll usingconventional techniques. The textured roll preferably imitates thetexture of sand, cementitious grout, mortar, cork, terrazzo or the likeas hereto before described. The time and temperature required for thegelling process must be sufficiently low in order not to initiatethermal crosslinking of the curable coating at these temperatures. If athermal crosslinking initiator is not used, electron beam crosslinkingtechniques can be employed as known by those skilled in the art.

[0016] To fix the embossed texture in those areas of the curable coatingoverlying the first and second printing inks containing thephotoinitiator, the curable coating containing the UV-curable acrylicmonomer or oligomer is crosslinked with ultraviolet light within anenclosure. The UV light decomposes the photoinitiator so as to form freeradicals or ions which are needed for crosslinking the monomer and/oroligomer moiety of the curable coating.

[0017] The product is then placed into a fusion oven where it is heatedto about 400° F. The effect is that those portions of the curablecoating which do not overlie either the first or second printing inkwill fluidize and relax such that the deformation of the curable coatingin these areas attributable to the mechanical embossing by means of thetextured roll disappear, i.e. smooth over. Additionally, that portion ofthe foamable plastic layer which does not underlie the second printingink containing an inhibitor, foams and expands. Any of the monomer oroligomer left unreacted after leaving the UV enclosure can be cured bythe thermal initiator optionally added to the curable coating. It isimportant to select this thermal initiator so that it begins toefficiently cure the unreacted monomer or oligomer after the laterportions smooth over.

[0018] The product may then be subjected to a second mechanicalembossing step, again by conventional techniques, wherein anothertexture such as the natural look of stone, wood or the like, ashereinbefore described, is applied to the surface of the curable coatingwhich has smoothed out. Following this step the product can optionallybe coated with a performance coating such as acrylic polyurethane.

[0019] An important feature of the process and product of the presentinvention is that the entire surface of the product may be initiallytextured in the first mechanical embossing step without necessitating aspecial patterned texturing roller controlled in register with thedesign or decoration of the surface covering. This is because thesurface areas of the curable coating which are not fixed after the firstmechanical embossing step will be softened during the subsequent fusionand expansion treatment and will become smooth because of heatrelaxation of plastic memories as taught in U.S. Pat. No. 3,887,678.

[0020] A product having the construction illustrated in FIGS. 2 to 4 isprepared by the process of FIG. 1. Referring to FIG. 2, a foamableplastic layer 1 containing a foaming agent is applied over a sheetsubstrate 2. The combination is then heated to gel the plastic layer 1.A first printing ink 3 which contains a photoinitiator and a secondprinting ink 4 which contains an expansion inhibitor and aphotoinitiator are applied in a first and second pattern, respectively,to gelled plastic layer 1. A clear liquid curable coating 5 (see FIG. 3)is applied over the entire surface of gelled plastic layer 1 and thefirst and second printing inks 3, 4. After heating the curable coating 5to gel and soften it, the softened curable coating 5 is mechanicallyembossed in a first embossing step with a textured roll to create afirst texture 6. The textured curable coating is then subjected toultraviolet light 7 and the product fused in an oven to cause thatportion of the curable coating 5 which does not overlie the printinginks 3, 4 to smooth out so that the textures attributable to the firstmechanical embossing step disappear in those areas (see FIG. 4).Furthermore, those portions of the gelled plastic layer 1 which do notcontain the inhibitor applied with the second printing ink 4, foam andexpand. The surface areas of the curable coating which have smoothed outare then mechanically embossed in a second embossing step to create asecond texture 8. The product may then be optionally coated with aperformance coating (not shown).

[0021] Each component of the product and each step of the process of theinvention will now be described with reference to various preferred andalternative embodiments.

The Substrate

[0022] The substrate is a relatively flat, fibrous or non-fibrous,backing sheet material, such as a fibrous, felted or matted, relativelyflat sheet of overlapping, intersecting fibers. The substrate can, ifdesired, comprise felts or papers which are woven or non-woven. It cancomprise knitted or otherwise fabricated textile material or fabricsmade from cellulose, glass, natural or synthetic organic fibers, ornatural or synthetic inorganic fibers, or supported or non-supportedwebs or sheets made therefrom, or filled or unfilled thermoplastic orthermoset polymeric materials. It can also comprise a compact layer.These and other substrate base materials are well known in the art andneed not be further detailed here.

The Foamable Plastic Layer

[0023] The foamable plastic layer, when used, can be comprised of anysuitable material known in the art for producing foamed plastic layerson a substrate, but is typically a polyvinylchloride (“PVC”) plastisol,an organosol, a polyolefin, an ionomer, plasticized PVC or thermoplasticrubber. This layer can be pigmented or free of pigmentation. If thelayer is pigmented, a color is preferably selected which is the averageof the colors of the end product so that the appearance and aestheticsof the product are maintained during its working life. To one skilled inthe art, the average color means the color perceived when one looks at asurface from a distance of more than about five feet.

[0024] The foamable plastic layer may include any of the various PVCresin materials normally used in connection with coating of decorativesheet materials and may specifically include, but are not limited to,those described in U.S. Pat. No. 3,458,337. While a suitable foamingagent or blowing agent as taught by the above-mentioned patent may beused, a blend of azodicarbonamide (“ABFA”) and p,p′oxybis (benzenesulfonyl hydrazide) (“OBSH”) foaming agents can be used instead.Additional conventional ingredients such as stabilizers, foaming orblowing agent catalysts, etc. can be used, of course the catalyst isrequired if chemical inhibition is required. Although the preferredfoamable plastic layer is a PVC homopolymer resin, other vinyl chlorideresins can be employed. Other synthetic resins are suitable such aspolystyrene, substituted polystyrene (preferably wherein thesubstituents are selected from the group consisting of alkyl having 1-10carbons, preferably 1-4 carbons, and aryl having 6-14 carbons),polyolefins such as polyethylene and polypropylene, acrylates andmethacrylates, polyamide, polyesters and any other natural or syntheticresin.

[0025] The composition of the foamable plastic layer must be compatiblewith the underlying substrate and the printing inks and, when gelled,must provide a smooth and uniform surface for the first and secondprinting inks. The composition also must be otherwise compatible withthe overall product composition and, therefore, within the principles ofthis invention. As indicated, it is not essential that a plastisol beused as the foamable plastic layer. Organosols and aqueous latexes arealso of use, employing as the dispersing or suspending media, organicsolvents and water, respectively, rather than plasticizers as in thecase of a plastisol.

[0026] The foamable plastic layer is substantially uniformly applied inits liquid state to the underlying substrate by conventional means suchas a knife-over roll coater, direct roll coater, rotary screen, drawdown bar, reverse roll coater or wire wound bar. The particular meansfor applying the foamable plastic layer does not relate to the essenceof the invention, and any suitable coating means can be employed.

[0027] The thickness of the foamable, liquid plastic layer as it isapplied to the underlying surface is substantially uniform and is in therange from about 2 to about 30 mils, preferably from about 6 to about 16mils. The layer can be thicker or thinner as may be required by theparticular product application.

[0028] Instead of a foamable plastic layer, a plastic layer which doesnot contain a foaming or blowing agent can be applied to the underlyingsubstrate in the same manner as described above.

Gelling

[0029] After the foamable, liquid, plastic layer containing a foamingagent is applied over the substrate, the combination is heated for aperiod of time and at a temperature sufficient to gel the plastic layer,but not sufficient to activate or decompose the blowing or foamingagent. This can be done in an oven or on a heated chrome drum. If anoven is used for the gelling step, a residence time in the oven fromabout 0.5 minutes to about 3.5 minutes at an oven temperature from about180° F. to about 400° F. will give good results. If a chrome drum isused, a dwell time on the drum from about 8 seconds to about 30 secondsat a drum temperature of from about 180° F. to about 350° F. will givegood results. The higher temperatures are used with shorter residence ordwell times and lower temperatures with longer times. The layer is thencooled to provide a surface suitable for printing. Cooling is generallyaccomplished by contacting the surface of the foamable, gelled plasticlayer (and sometimes the underside of the substrate) with one or morecooling drums. Ambient or chilled water is circulated through the drums.Cooling may be enhanced with the use of fans or blowers. The samegelling process can be employed if the plastic layer does not contain afoaming or blowing agent as will be apparent to those skilled in theart. Also calendering or extrusion techniques followed by laminationonto a substrate of a sheet of similar formulations as above can be usedto prepare the printable layer.

The Printing Inks

[0030] In the foregoing preferred embodiment, a first printing inkcontaining a photoinitiator is applied in a first pattern or design ontothe gelled plastic layer. Then, a second printing ink containing aphotoinitiator and an expansion inhibitor is applied in a second patternor design onto the gelled plastic layer. Suitable printing inks includethose normally used in the manufacture of surface coverings. Theseinclude plastisol, solvent-based systems and water-based systems. Ofcourse, other printing inks which do not contain a photoinitiator or anexpansion inhibitor can be applied to obtain design objectives.Furthermore, it is not necessary to employ both the first and secondprinting inks as long as at least one printing ink with a photoinitiatoris employed. Either ink can be employed alone or in combination withother printing inks which do not contain a photoinitiator or anexpansion inhibitor. If no foamable plastic layer is employed then inkshaving an expansion inhibitor are not employed.

[0031] The first, second and other printing inks may be pigmented ornon-pigmented and may include organic pigments or inorganic pigmentparticles such as titanium dioxide, iron oxide, carbon black, mica,pearlescent and the like. Decorative reflective particles such asmetallics, may also be included as part of one or more printing inkcompositions. The types and components of the first, second and otherprinting inks can be the same or different.

[0032] The first and second printing inks contain a photoinitiator. Byway of example only, and not by limitation, the following ultravioletcrosslinking initiators may be used in accordance with the presentinvention: benzophenone, 2-chloro-thioxanthone, 2-methyl-thioxanthone,2-isopropyl-thioxanthone, benzoin, 4,4′-dimethoxybenzoin, benzoin ethylether, benzoin isopropyl ether, benzyldimethylketal,1,1,1-trichloro-acetophenone,1-phenyl-1,2-propanedione-2-(ethoxycarbonyl)-oxide,diethoxyacetophenone, and dibenzosuberone. The inks containing thephotoinitiators should contain about 1% to about 15%, preferably about10% by weight of photoinitiator.

[0033] The second printing ink also contains an expansion inhibitor. Byway of example only, and not by limitation, the following inhibitors maybe used in accordance with the present invention: benzotriazole,tolyltriazole, fumaric acid and trimellitic anhydride. The specificexpansion inhibitor which is used does not relate to the essence of thepresent invention and many other suitable and acceptable expansioninhibitors are available to one of ordinary skill in the art.

[0034] Printing of the inks onto the gelled plastic layer can beeffected by rotogravure, flexigraphic, screen printing, pad or knurledprinting, or other printing techniques conventionally employed in makingfloor or wall covering products.

[0035] When the second printing ink is applied to the gelled plasticlayer, the inhibitor present in the second printing ink migrates intothe gelled plastic layer beneath the second printing ink.

[0036] It will be appreciated that in the present invention that oneink, two inks or multiple inks may be used to print patterns or designson the substrate or on the gelled plastic layer. Each ink may optionallycontain a photoinitiator and/or an inhibitor. Of course ink withoutphotoinitiators or inhibitors can be used to obtain design objectives.It will also be appreciated that the order of printing is not criticaland is not to be construed as a limitation of the invention.Furthermore, it is to be understood that the print areas of the inks mayoverlap.

The Curable Coating

[0037] After the printing inks have been applied to the gelled plasticlayer, a liquid curable coating containing a crosslinkable photopolymeror monomer, such as an acrylic monomer or oligomer, and optionally athermal crosslinking initiator, is applied over the entire surface ofthe gelled plastic layer including over the first and second printinginks. In the preferred embodiment, the photoinitiators residing in thefirst and second printing inks then migrate into that portion of thecurable layer which was applied over the first and second printing inks.The curable layer may comprise a plastisol and, as used herein, the term“plastisol” is generally intended to cover a relatively high molecularweight polyvinylchloride (“PVC”) resin dispersed in one or moreplasticizers. A plastisol upon heating or fusing forms a toughplasticized solid. For purposes of this specification, plastisolcompositions are also intended to include organosols. A clear calenderedor extruded film of the same composition can also be used. It is adheredonto the printed gelled plastic layer by means known in the art, forexample, laminating.

[0038] The thickness of the curable coating as it is applied in itsliquid, tacky, ungelled state to the gelled plastic layer and inks issubstantially uniform and is in the range from about 2 mils to about 40mils, preferably from about 8 mils to about 20 mils. The coating can bethinner or thicker as may be required by the particular productapplication. The curable coating is applied by conventional means suchas described above with respect to application of the foamable plasticlayer. The particular means for applying the curable coating does notrelate to the essence of the invention and any suitable coating meanscan be employed.

[0039] The curable coating is preferably a clear (transparent) layer butit can be slightly tinted as long as it remains translucent and allowsUV penetration. The curable coating may also contain solid particulatessuch as chips, flakes, flitters, etc.

[0040] By way of example only, cross-linkable monomers suitable for usein connection with the present invention include, but are not limitedto, the following compounds: ethylene glycol dimethacrylate, ethyleneglycol diacrylate, diethylene glycol dimethacrylate, diethylene glycoldiacrylate, triethylene glycol dimethacrylate, triethylene glycoldiacrylate, tetraethylene glycol dimethavrylate, tetraethylenediacrylate, polyethylene glycol dimethacrylate, polyethylene glycoldiacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycoldimethacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycoldiacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate,neopentyl glycol diacrylate, neopentyl glycol dimethacrylate,(ethoxylated) bis-phenol A dimethacrylate, divinylbenzene,divinyltoluene, trimethylolpropane trimethacrylate, trimethylolpropanetriacrylate, pentaerythritol triacrylate, glyceryl trimethacrylate,pentaerythritol tetracrylate and pentaerythritol tetramethacrylate.

[0041] The curable coating containing a crosslinkable reagent, monomerand/or oligomer should contain 2 to 40%, preferably about 10% by weightof monomer.

[0042] By way of example only, cross-linkable oligomers suitable for usein connection with the present invention include, but are not limited tothe oligomers described in U.S. Pat. No. 6,146,711.

Heating and First Embossing Step

[0043] To prepare the curable coating for mechanical embossing, thecurable coating is gelled by heating. The product is passed through anoven maintained at a temperature from about 160° F. to about 340° F.,preferably from about 275° F. to about 320° F., for a residence timefrom about 0.75 to 3 minutes. A hot air recirculating oven and/or aninfrared (“IR”) oven operated at these temperatures is generallyemployed. The product surface is then softened by heat, preferably bymeans of an IR oven, to a temperature from about 300° F. to 340° F.,preferably 320° F., as measured by a pyrometer, before the embossingrollers nip.

[0044] Once the curable coating has been adequately softened, it ismechanically embossed by means of a textured roll which imitates thetexture of sand, cementitious grout, mortar or the like as hereinbeforedescribed. The textured roll operates under a pressure that depends uponthe degree of texturing desired as is known by a person having ordinaryskill in the art.

Ultraviolet (“UV”) Curing

[0045] The product may be cooled before it is UV cured. It is not arequirement but it reduces the fumes in the UV enclosure which wouldreduce the UV transference to the product. Once the first embossing stephas been completed, the product enters an enclosure where it issubjected to the emissions of a UV lamp to cross-link that portion ofthe curable coating overlying the first and second printing inkscontaining a photoinitiator. This step fixes the embossed texture intothe surface areas of the plastisol disposed over the ink containing thephotoinitiator.

[0046] The UV curing step can occur in a UV reactor wherein the productis subjected to about 100 to about 1500 millijoules per squarecentimeter (mJ/sq. cm.), preferably about 1000 mJ/sq. cm., of focused ordiffused UV radiation, preferably focused radiation, at about 100 toabout 400 watts per inch of adjustable power using H-type, V-type, orD-type bulbs, preferably H-type bulbs. Such a UV reactor is availablefrom IST (Germany).

Fusion and Expansion

[0047] After portions of the curable coating have been cured in theabove-described enclosure, the product obtained therefrom is introducedto a fusion oven maintained at a temperature from about 350° F. to about430° F., preferably about 400° F. The product has a residence time inthe oven from about 1 to about 3 minutes. A hot air recirculating ovenand/or an IR oven operated at these temperatures is generally employed.

[0048] Subjecting the product to these temperatures for this period oftime fuses the substrate, the plastic layer, the printing inks and thecurable coating together and foams and expands those portions of thefoamable plastic layer which do not underlie the second printing inkwhich contains an inhibitor. Furthermore, those portions (i.e., surfaceareas) of the curable coating which were not previously cured, i.e., donot overlie either the first or second printing inks, will relax suchthat the deformation and texturing in the still curable coating in theseareas attributable to the first mechanical embossing step to thisportion disappear, i.e. smooth over. More particularly, during this stepthat portion of the curable coating which has not been cured(crosslinked) during UV exposure undergoes relaxation which has theeffect of smoothing the textured surface, while that portion of thecurable coating that has been cured during UV curing retains itstextured appearance. This relaxation phenomenon is one that requires thefirst overall embossing to be conducted at a temperature as low aspossible to minimize the plastic component of the mechanical deformationinduced in the curable coating by the embossing roll.

Second Embossing Step (Optional)

[0049] After being removed from the fusion oven, those portions of thecurable coating (now the cured coating) which do not overlie theprinting inks and hence have smoothed out, are mechanically embossed asecond time by means, known to those of ordinary skill in the art, suchas a texture roll, or other conventional means containing textures suchas the natural looking texture of stone, wood or the like as heretobefore described.

Performance Coating

[0050] After fusion and expansion or after the optional secondmechanical embossing step is completed, the product is cooled to fromabout 60° F. to about 180° F. by conventional means such as air or watercooled drums. Then a performance coating such as acrylic polyurethanecan optionally be applied to the product.

[0051] The following non-limiting examples provide particular andpreferred embodiments of the process and product of the presentinvention.

Use of Calendered or Extruded Layers

[0052] As noted above, calendered or extruded sheets can be employed aslayers in place of any one or both of the foamable layer and/or curablelayer. When a foamable sheet is employed it is formed by calendering oran extrusion die at a temperature below the decomposition temperature ofthe foaming or blowing agent, or the catalyzed foaming or blowing agent.When a sheet is used in place of the curable layer, it is processed bycalendering or an extrusion die under conditions which do notsignificantly decompose the peroxide, so that it remains a curablelayer. When sheet materials are used they are laminated to theunderlying surface of the product by employing techniques known by thosehaving ordinary skill in the art.

EXAMPLE 1

[0053] A ceramic pattern having grout lines was printed on a foamablebase. In the grout lines of the pattern the ink printed thereincontained an inhibitor and a photoinitiator (P1). A 0.010 inch thickcoating was applied of a clear plastisol (A1) containing a curableacrylic monomer and another radical generator (peroxide) to heat set thefree monomer left unreacted when the product left the UV reactor.

[0054] The plastisol (A1) was heated to a temperature of 300° F. to gel.Following gelling the surface was heated with IR to 320° F. to softenthe surface for mechanical embossing. Then the entire surface of theproduct was mechanically embossed with a sandy textured roll (E1).

[0055] To fix the embossed texture in the plastisol wear layer areaoverlaying the ink (P1), the gelled surface of the product was subjectedto UV light at an irradiation of 1000 mJ/sq. cm., H type bulb, tocrosslink the monomer.

[0056] To create a relief, the product was conveyed into a fusion ovenwhere it was heated to 400° F. for 2 minutes to blow the foamable layerand create depressions in the areas printed with P1 ink. The areas ofthe embossed and crosslinked plastisol wear layer disposed over theprinted grouts kept the texture as fixed by the UV processing and theremainder of the surface was smoothed out by relaxation.

[0057] This process made a grout appearance imitating thethree-dimensional texture of a real cementitious grout. Furthermore, asa printing technique was used to locate the texture, the product wasconsequently embossed in register.

[0058] After the product was fused, another texture was applied bymechanical embossing of the raised portions of the product. Optionally,the product then can be coated with a polyurethane which can be cured byheat or by UV radiation. To apply this coating in a thin layer, the useof an air knife will maintain the initial texture of the uncoatedproduct. The product is then cooled and rolled.

[0059] In this example the ink formulation (P1) was as follows:Ingredients Quantity (Parts by weight) Clear vehicle 82 Inhibitor(tolyltriazole) 10 Photoinitiator (IRGACURE 2959) 8 Color Following thepattern

[0060] The wear layer formulation (A1) was as follows: IngredientsQuantity (parts by weight) SANTICIZER 377 400 TXIB 45 SARTOMER SR-350110 DICUP (10% solution in 21 SANTICIZER 377) Heat stabilizer 98Extender PVC 136 Paste PVC (75Kv) 930

EXAMPLE 2

[0061] A ceramic/slate pattern having grout lines was printed on afoamable base. In the grout lines of this pattern the ink contained aninhibitor and in the slate area a full tone was printed with an inkcontaining a photoinitiator (P2). A 0.014 inch thick coating of a clearplastisol (A2) containing a curable acrylic monomer and another radicalgenerator (peroxide) was applied to heat set the free monomer leftunreacted when the product leaves the UV reactor. Then the process ofExample 1 was followed but using an embossing roll (E2) that had a slatetexture instead of the sandy texture (E1). After the product was fusedand blown, it was cooled and rolled. The slate texture was only disposedover the areas of the product having the slate print. This gave a betterrendering of the original assembly of slate and ceramic.

[0062] In this example the wear layer formulation (A2) was as follows:Ingredients Quantity (parts by weight) SANTICIZER 377 400 TXIB 45SARTOMER SR-350 220 DICUP (10% solution in 21 SANTICIZER 377) HeatStabilizer 98 Extender PVC 136 Paste PVC (70Kv) 930

EXAMPLE 3

[0063] An old ceramic look pattern was printed on a foamable base. Inthe grout parts of this pattern the ink contained an inhibitor and aphotoinitiator (P1) and in some fields of the ceramic the ink containeda photoinitiator (P2). A 0.020 inch thick coating of a clear plastisol(A3) was applied containing a curable acrylic monomer and anotherradical generator (peroxide) to heat set the free monomer left unreactedwhen the product left the UV reactor. Then the process of Example 1 wasfollowed using the sandy texture (E1). After the product was fused andblown, the product was cooled and rolled. The appearance of the productwas like an old ceramic floor with worn surfaces by spots with athree-dimensional cementitious grout.

[0064] In this example the wear layer formulation (A3) was as follows:Ingredients Quantity (parts by weight) SANTICIZER 377 400 TXIB 45SARTOMER SR-350 220 DICUP (10% solution in 21 SANTICIZER 377) HeatStabilizer 98 Extender PVC 136 Paste PVC 930

EXAMPLE 4

[0065] On a flat compact base a wood pattern was printed comprisingplanks with ticking and joint lines. In the joint lines and in theticking parts of this pattern the ink contained a photoinitiator (P2). A0.004 inch thick coating was applied of a clear plastisol (A4)containing a curable acrylic monomer and oligomer and another radicalgenerator (peroxide) to heat set the free monomer and oligomer leftunreacted when the product left the UV reactor. Then the process ofExample 1 was followed but using an embossing roll (E3) that had a flat,dull texture instead of the sandy texture (E1). After the product wasfused, the product was cooled and rolled. The product had the appearanceof a more realistic wood parquet when compared with a laminated woodparquet.

[0066] In this example the wear layer formulation (A4) is as follows:Ingredients Quantity (parts by weight) STAHL U26253 75 SARTOMER SR-209550 DICUP (10% solution in 20 SARTOMER SR-209 Heat Stabilizer 60 PastePVC (75Kv) 1000

[0067] A surface covering and process for its manufacture has beenprovided which readily avoids the problems and shortcomings associatedwith the prior art. The preferred embodiment has been illustrated anddescribed. Further modifications and improvements may be made thereto asmay occur to those of ordinary skill in the art and all such changes asfall within the true spirit and scope of this invention are to beincluded within the scope of the claims to follow.

What is claimed is:
 1. A method of making a surface covering whichcomprises the sequential steps of: (a) applying over a substrate aplastic layer containing a foaming agent, (b) heating the plastic layerto a temperature which gells the plastic layer without activating thefoaming agent to form a gelled plastic layer having a surface, (c)applying to the surface of the gelled plastic layer a first printing inkcontaining a photoinitiator in a first pattern or a first design, (d)applying to the surface of the gelled plastic layer a second printingink containing a photoinitiator and an expansion inhibitor in a secondpattern or a second design, (e) applying a curable coating over thegelled plastic layer and the first and second printing inks, (f) gellingthe curable coating, (g) heating to soften the gelled curable coating,(h) mechanically embossing the softened curable coating, (i) activatingthe photoinitiator and curing the surface areas of the curable coatingdisposed over the first and second printing inks, (j) heating toactivate the foaming agent and fuse the curable coating, the plasticlayer and the substrate together, wherein foaming of the plastic layerunderlying the second printing ink is inhibited, and the mechanicalembossing in surface areas disposed over unprinted areas is relaxed, (k)optionally mechanically embossing the curable coating in areas that arenot disposed over the first and second printing inks.
 2. The method ofclaim 1 wherein the curable coating is cured following fusion bysubjecting the surface covering to electron beam radiation.
 3. Themethod of claim 2 wherein the surface covering is subjected to electronbeam radiation following mechanical embossing in step (k).
 4. The methodof claim 1 wherein the curable coating contains a thermal crosslinkinginitiator and the curable coating is cured by heat during fusion.
 5. Themethod of claim 1, further comprising applying a polyurethane coatingafter optionally mechanically embossing.
 6. The method of claim 1,wherein the surface covering is selected from the group consisting ofsheet flooring, tile and wall covering.
 7. The method of claim 1,wherein the surface covering is cooled prior to heating to soften thegelled curable coating.
 8. The method of claim 1, wherein the surfacecovering is cooled and then the surface is reheated to soften it priorto optionally mechanically embossing.
 9. The method of claim 1, whereinafter gelling the plastic layer the surface covering is cooled prior toapplying the printing ink.
 10. The method of claim 1, wherein saidcurable coating contains a thermal crosslinking initiator.
 11. Themethod of claim 7, wherein said thermal crosslinking initiator isperoxide.
 12. The method of claim 8, wherein said curable coatingcontains solid particulates.
 13. The method of claim 1, furthercomprising applying one or more than one additional printing ink(s) tothe surface of the gelled plastic layer.
 14. The method of claim 13,wherein one or more than one of said additional printing ink(s) containsa photoinitiator.
 15. The method of claim 13, wherein one or more thanone of said additional printing ink(s) contains an inhibitor.
 16. Themethod of claim 14, wherein one or more than one of said additionalprinting inks containing a photoinitiator also contains an inhibitor.17. A method of making a surface covering which comprises the sequentialsteps of: (a) applying a plastic layer over a substrate, (b) heating theplastic layer to a temperature which gells the plastic layer, (c)applying a printing ink containing a photoinitiator onto the gelledplastic layer in a pattern or a design, (d) applying a curable coatingover the gelled plastic layer and the printing ink, (e) gelling thecurable coating, (f) heating to soften the gelled curable coating, (g)mechanically embossing the softened curable coating, (h) activating thephotoinitiator and curing the curable coating disposed over the printingink, (i) heating to cure uncured portions of the curable coating andfuse the thereby cured coating, the plastic layer and the substratetogether.
 18. The method of claim 17 further comprising mechanicallyembossing the cured coating in areas that are not disposed over theprinting ink.
 19. The method of claim 17, further comprising applying apolyurethane coating after mechanically embossing the cured coating thatis uncured.
 20. The method of claim 17, wherein the surface covering isselected from the group consisting of sheet flooring, tile and wallcovering.
 21. The method of claim 17, wherein the surface covering iscooled prior to curing the curable coating.
 22. The method of claim 17,wherein the surface covering is cooled following curing the curablecoating.
 23. The method of claim 17, wherein after gelling the plasticlayer the surface covering is cooled prior to applying the printing ink.24. The method of claim 17, wherein said curable coating contains athermal crosslinking initiator.
 25. The method of claim 17, wherein saidthermal crosslinking initiator is peroxide.
 26. The method of claim 17,wherein said curable coating contains solid particulates.
 27. The methodof claim 17, further comprising applying one or more than one additionalprinting ink(s) onto the gelled plastic layer before applying saidcurable coating.
 28. The method of claim 27, wherein one or more thanone of said additional printing ink(s) contains a photoinitiator and/oran inhibitor.
 29. The method of claim 17 wherein the curable coatingcomprises a curable acrylic monomer and/or oligomer.
 30. The method ofclaim 17 wherein the plastic layer contains a foaming or blowing agent,one or more than one printing ink(s) further contains an inhibitor,heating to gel the plastic layer is not sufficient to activate thefoaming or blowing agent, and heating in step (i) is sufficient toactivate the foaming or blowing agent and relax the mechanical embossingin surface areas disposed over areas not printed with an ink comprisinga photoinitiator.
 31. A surface covering which comprises: (a) asubstrate, (b) a foamed and chemically embossed plastic layer overlayingthe substrate, (c) an ink containing a photoinitiator printed in adesign on said foamed plastic layer, (d) a cured coating or a curedlayer overlaying the foamed plastic layer and ink wherein the portion ofthe cured coating or the cured layer disposed over the ink is chemicallyand mechanically embossed.
 32. The surface covering of claim 31 whereinthe ink also contains an inhibitor.
 33. The surface covering of claim 31wherein the portion of the cured coating or cured layer which is notdisposed over the ink is mechanically embossed with a texture differentfrom the mechanically embossed portion of the cured coating disposedover the ink.
 34. The surface covering of claim 31 further comprising apolyurethane coating overlaying the cured coating or cured layer.
 35. Asurface covering which comprises: (a) a substrate, (b) a plastic layeroverlaying the substrate, (c) an ink containing a photoinitiator printedin a design on said plastic layer, (d) a cured coating or a cured layeroverlaying the plastic layer and the ink wherein the cured coating orthe cured layer overlaying the ink is mechanically embossed.
 36. Thesurface covering of claim 35 further comprising a polyurethane coatingoverlaying the cured and embossed cured coating or cured layer.
 37. Amethod of making a surface covering which comprises the sequential stepsof: (a) applying over a substrate a plastic layer containing a foamingagent, (b) applying to the surface of the plastic layer a first printingink containing a photoinitiator in a first pattern or a first design,(c) applying to the surface of the gelled plastic layer a secondprinting ink containing a photoinitiator and an expansion inhibitor in asecond pattern or a second design, (d) applying a curable layer over theplastic layer and the first and second printing inks, (e) heating tosoften the curable layer, (f) mechanically embossing the softenedcurable layer, (g) activating the photoinitiator and curing the surfaceareas of the curable layer disposed over the first and second printinginks, (h) heating to activate the foaming agent, cure uncured portionsof the curable layer, wherein foaming of the plastic layer underlyingthe second printing ink is inhibited, and the mechanical embossing insurface areas disposed over unprinted areas is relaxed, (i) optionallymechanically embossing the cured coating in areas that are not disposedover the first and second printing inks.
 38. The method of claim 37,further comprising applying a polyurethane coating after optionallymechanically embossing.
 39. The method of claim 37, further comprisingapplying additional printing ink(s) after application of said secondprinting ink and before applying said plastisol coating.
 40. The methodof claim 37 wherein the plastic layer is applied as a liquid followed byheating the plastic layer to a temperature which gels the plastic layerwithout activity the foaming agent to form a gelled plastic layer havinga surface.
 41. The method of claim 37 wherein the plastic layer isadhered over the substrate.
 42. The method of claim 41 wherein theplastic layer is adhered by laminating.
 43. The method of claim 37wherein the curable layer is applied as a liquid followed by gelling thecurable layer.
 44. The method of claim 37 wherein the curable layer isadhered over the plastic layer and the first and second printing inks.45. The method of claim 44 wherein the curable layer is adhered bylaminating.